A green low temperature (90 degrees C) route was proposed for the synthesis of CuO nanoflakes, using CuCO3 center dot Cu(OH)(2) powder and H2O2 aqueous solution (6 vol.%) as the starting materials. The characterization results from X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electronic microscopy revealed that the as-synthesized product was pure monoclinic phase CuO nanoflakes. UV-vis absorption spectrum showed that the as-synthesized CuO nanoflakes had an optical band gap of about 2.15 eV. The present method points out a promising green, simple, low cost and low temperature way of converting the natural malachite ore (whose composition is CuCO3 center dot Cu(OH)(2)) into multifunctional CuO nanomaterials. (C) 2012 Elsevier B.V. All rights reserved.